公歷轉換農歷算法

周末試着做了一個公歷轉農歷的例子，執行結果如下：

代碼如下：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace AlgorithmPractice
{
    public partial class 公歷轉農歷 : Form
    {
        public 公歷轉農歷()
        {
            InitializeComponent();
        }
        private void 公歷轉農歷_Load(object sender, EventArgs e)
        {
            BindYear();
            this.cbYear.SelectedItem = DateTime.Now.Year;
            this.cbMonth.SelectedItem = DateTime.Now.Month;
            this.cbDay.SelectedItem = DateTime.Now.Day;
            btnChange_Click(sender,e);
        }
        //綁定年份
        public void BindYear()
        {
            List<int> arrYear = new List<int>();
            for (int i = 0; i <= 2101 - 1901; i++)
            {
                arrYear.Insert(i, 1901 + i);
            }
            this.cbYear.DataSource = arrYear;
        }
        //月份隨年份而變
        private void cbYear_SelectedIndexChanged(object sender, EventArgs e)
        {
            int[] year1901 = { 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 };
            int[] year2101 = { 1 };
            int[] yearOther = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 };
            if (this.cbYear.Text == "1901")
            {
                this.cbMonth.DataSource = year1901;
            }
            else if (this.cbYear.Text == "2101")
            {
                this.cbMonth.DataSource = year2101;
            }
            else
            {
                this.cbMonth.DataSource = yearOther;
            }
        }
        //開始轉換
        private void btnChange_Click(object sender, EventArgs e)
        {
            try
            {
                string date = this.cbYear.Text + "-" + cbMonth.Text + "-" + cbDay.Text;
                DateTime dt = Convert.ToDateTime(date);
                this.lblNongLi.Text = SolarToChineseLunisolarDate(dt);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
        /// <summary>
        /// 公歷轉為農歷的函數
        /// </summary>
        /// <param name="solarDateTime">公歷日期</param>
        /// <returns>農歷的日期</returns>
        public static string SolarToChineseLunisolarDate(DateTime solarDateTime)
        {

            //微軟的ChineseLunisolarCalendar 方法支持時間范圍是[1901－2-19,2101-1-28]
            System.Globalization.ChineseLunisolarCalendar cal = new System.Globalization.ChineseLunisolarCalendar();
            int year = cal.GetYear(solarDateTime);//農歷年份
            int month = cal.GetMonth(solarDateTime);//有閏月時該值可能為13，即leapMonth <= month ? month - 1 : month表示實際農歷月份
            int day = cal.GetDayOfMonth(solarDateTime);//農歷天數
            int leapMonth = cal.GetLeapMonth(year);//此年份閏幾月，閏n月則返回n+1,如閏4月返回值為5；沒有閏月返回0
            String impday = "";//一年中的農歷節日
            String leapMonthStr = leapMonth > 0 ? "(閏" + (leapMonth - 1).ToString() + "月)" : "";//閏月份
            int monthtrue = leapMonth > 0 && leapMonth <= month ? month - 1 : month;//把閏月計算進去之后真正的農歷月份
            if (monthtrue == 1 && day == 1)
            {
                impday = "春節";
            }
            else if (monthtrue == 5 && day == 5)
            {
                impday = "端午";
            }
            else if (monthtrue == 8 && day == 15)
            {
                impday = "中秋";
            }
            String month2 = String.Format("{0}{1}月", month == leapMonth ? "閏" : ""
                                , "無正二三四五六七八九十冬臘"[monthtrue]
                                );
            String day2 = string.Format("{0}{1}"
                    , "初十廿三"[day == 10 ? 0 : day / 10]
                        , "十一二三四五六七八九"[day % 10]
                        );
            String date = year + "年" + month2 + day2;

            if (impday != "")
            {
                return date + leapMonthStr + " " + "祝您" + impday + "節快樂 ^-^";
            }
            else
                return date + leapMonthStr;
        }
        //日子隨月份改變
        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (String.IsNullOrEmpty(this.cbYear.Text.Trim()))
            {
                MessageBox.Show("年份不能為空！");
                return;
            }
            try
            {
                int[] month31 = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 };
                int[] month30 = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 };
                int[] month29 = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 };
                int[] month28 = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28 };
                int[] month190102 = { 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 };
                int[] month210101 = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28 };
                String strmonth = this.cbMonth.Text.Trim();
                String stryear = this.cbYear.Text.Trim();
                if (stryear == "1901" && strmonth == "2")
                {
                    this.cbDay.DataSource =month190102;
                }
                else if (stryear == "2101" && strmonth == "1")
                {
                    this.cbDay.DataSource = month210101;
                }
                else
                {
                    if (strmonth == "1" || strmonth == "3" || strmonth == "5" || strmonth == "7" || strmonth == "8" || strmonth == "10" || strmonth == "12")
                    {
                        this.cbDay.DataSource = month31;
                    }
                    else if (strmonth == "4" || strmonth == "9" || strmonth == "6" || strmonth == "11")
                    {
                        this.cbDay.DataSource = month30;
                    }
                    else if (strmonth == "2")
                    {
                        if (System.DateTime.IsLeapYear(Convert.ToInt32(this.cbYear.Text.Trim())) == true)
                        {
                            this.cbDay.DataSource = month29;//閏年
                        }
                        else
                        {
                            this.cbDay.DataSource = month28;
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        
    }
}